Fire-extinguishing aerosol composition for common electric apparatuses

ABSTRACT

A fire-extinguishing aerosol composition for common electric apparatuses is disclosed, which includes oxidant, combustible, adhesive and additive. The composition of the present invention is characterized in that the oxidant is the mixture of the potassium salt and the strontium salt, in which the content of the potassium salt oxidant is more than or equal to 15 mass % to less than 20 mass % of the total mass of the composition, and the content of the strontium salt oxidant is more than 48 mass % to less than or equal to 52 mass % of the total mass of the composition. In the fire-extinguishing aerosol composition of the present invention, the mean particle diameter of all components is less than or equal to 50 μm. After quenching the fire in a space with the heavy current electric apparatus, the fire-extinguishing aerosol composition of the present invention can ensure that the insulation resistance of the common electric apparatus is ranged from 20MΩ to 100MΩ. The fire-extinguishing aerosol composition of the present invention is more reasonable than the prior art, friendly to the environment, and applicable to the common electric apparatuses.

FIELD OF THE INVENTION

The present invention belongs to the technical field offire-extinguishing compositions, and relates to a fire-extinguishingaerosol composition suitable for extinguishing of Type A or Type B firein relatively enclosed spaces, in particular, to a fire-extinguishingaerosol composition suitable for general electric apparatuses.

BACKGROUND OF THE INVENTION

The aerosol fire-extinguishing techniques emerged in the 1990s arefire-extinguishing techniques that are based on the intenseoxidation-reduction reaction between oxidant and fuel, and utilize thechemical reaction of the resulted active inhibiting agent to preventcombustion and chain reaction of free radical groups in the flame, so asto achieve the purpose of fire-extinguishing. The aerosolfire-extinguishing technique mainly comprises three types: hot aerosolfire-extinguishing technique, cold aerosol fire-extinguishing technique,and fine water mist fire-extinguishing technique, among which hotaerosol fire-extinguishing techniques comprise pyrotechniccompound-based hot aerosol fire-extinguishing techniques and water-basedhot aerosol fire-extinguishing techniques. At present, most pyrotechniccompound-based hot aerosol fire-extinguishing techniques employ solidpyrotechnic compound extinguishing agents composed of oxidant,combustible, adhesive, and combustion rate controller. As a substitutefor halon, pyrotechnic compound-based hot aerosol extinguishing agentshave significant advantages over other types of extinguishing agents,for example, they have high extinguishing efficiency, the structure offire-extinguishing equipment is simple, there is no need for pressurecontainer, the fire-extinguishing units can be modularized and combinedas required, the extinguishing agents can be stored at normaltemperature and normal pressure, the fire-extinguishing equipment iseasy to service and maintenance, the extinguishing agents have longshelf life and low cost, no ozone depletion potential (ODP=0), lowgreenhouse warning potential (GWP), and high cost/performance. Theseextinguishing agents are favored in the market and can driveimplementation of the halon replacement program.

In the prior art, nitrate alkali salts, especially potassium nitrate,are the first choice for oxidant in most pyrotechnic compound-based hotaerosol fire-extinguishing techniques, because they can meet the mostrequirements of the principles for component selection. In existingtechniques of fire-extinguishing aerosol composition withsingle-component potassium nitrate as the oxidant, the mostrepresentative hot aerosol fire-extinguishing agent techniques are thosedisclosed in the Russian series patent group, such as patentapplications RU2230726, RU2184587, RU2214848, RU2150310, RU2108124,RU2091106, RU2076761, RU2151135, RU2116095, RU2006239, RU2022589; andpatent applications in other countries, such as WO0158530, WO9733653,WO9423800, U.S. Pat. No. 5,831,209, U.S. Pat. No. 6,042,664, U.S. Pat.No. 6,264,772, U.S. Pat. No. 5,573,555, U.S. Pat. No. 6,116,348, etc.;what take the second position are fire-extinguishing aerosol compositiontechniques that employ bi-component or multi-component oxidants mainlycomposed of potassium nitrate and/or potassium perchlorate and/orassisted with nitrates or carbonates of other alkali metals or alkalineearth metals, as disclosed in patent applications such as CA2250325,DE19915352, UA7773, EP0561035, WO2005023370, RU2157271, RU2098156,US20020121622, U.S. Pat. No. 5,423,385, U.S. Pat. No. 5,492,180, U.S.Pat. No. 5,425,426, U.S. Pat. No. 6,277,296, etc. As for selection ofcombustibles, there is a wide range of substances that can meet theprinciple for component selection. The organic or inorganic combustiblesthat can meet the requirements are selected on the premise of ensuringnegative oxygen balance design, such as the combustibles disclosed inpatent applications RU218458, RU2214848, US20010011567, U.S. Pat. No.6,264,772, RU2157271, RU2050878, U.S. Pat. No. 5,831,209, WO9733653,EP0561035, etc. With respect to the water-based hot aerosol firextinguishing agent techniques, the oxidants and combustibles selectedare typically composed of ammonium nitrate, ammonium perchlorate,potassium nitrate, strontium nitrate, or guanidine nitrate and likecomponents that can generate gas, moisture content, and metal solidparticles on the premise of ensuring high oxygen balance design, such asthose disclosed in patent applications U.S. Pat. No. 6,277,296, U.S.Pat. No. 6,093,269, U.S. Pat. No. 6,045,726, U.S. Pat. No. 6,019,861,U.S. Pat. No. 5,613,562, etc.

Above patented hot aerosol fire-extinguishing techniques werefire-extinguishing products favored in recent years for theiradvantageous features of high extinguishing efficiency, low price,convenient maintenance, etc. However, as the market application andfurther development of actual products, many drawbacks of existingtechniques and products described above have been discovered. Recently,a great deal of application practices and research efforts have shown:fire-extinguishing agents with single-component or multi-componentoxidants mainly composed of potassium nitrate produce strongly alkalineconductive substances (e.g., potassium hydroxide) that can causesecondary damage to the space and objects to be protected, although theyhave high fire-extinguishing efficiency. Especially, the moisturecontent and metal oxides produced by water-based hot aerosolfire-extinguishing agents tend to form strongly alkaline conductivesubstances, which may lead to damage or erode general electricapparatuses in instrument rooms, control rooms, generator rooms, batterycabinets, communication base stations, transformer substations, etc.,and thereby result in irreparable consequences, when these products areused to extinguish fire in such environments. Moreover, if the resultingnitrous oxide can't be decomposed timely, it will have toxicity tohuman's nerve system. In view of the problems, some researchinstitutions and manufacturers have put forth some hot aerosolfire-extinguishing schemes that have taken both fire-extinguishingefficiency and secondary damages into consideration, such as thetechnical scheme of aerosol fire-extinguishing agent with strontiumnitrate as the only oxidant, as disclosed in patent applicationCN200510105449. However, the most severe drawback of that technicalscheme is: though the technical scheme reduces secondary damages togeneral electric apparatuses, it severely degrades thefire-extinguishing efficacy of the fire-extinguishing agent. Thefire-extinguishing compositions disclosed in patent application U.S.Pat. No. 5,613,562 and U.S. Pat. No. 5,609,210 employ strontium nitrateas the oxidant, which mainly acts as a power source to gasify anotherfire-extinguishing liquid that contains C—F bonds and C—H—F bonds andthen spurt the liquid/gas to the fire; however, the resultinghydrofluoric acid has not only high toxicity but also highcorrodibility. That technique belongs to a water-based hot aerosolfire-extinguishing technique. Though the fire-extinguishing compositiondisclosed in patent application U.S. Pat. No. 6,019,861 containspotassium nitrate or strontium nitrate component, the potassium nitrateor strontium nitrate component is only used as an additive or aco-oxidant, and the main oxidant is ammonium nitrate that must besubjected to phase stabilization; in addition, the main purpose of thepotassium nitrate or strontium nitrate component is to provide highquality dilating gas. Though the fire-extinguishing composition has anadvantage of lower temperature when it is used in the fire-extinguishingtechnique, it degrades the combustion rate and the gas generation rate.A pyrotechnic gas generating agent with high oxygen balance is disclosedin patent application U.S. Pat. No. 6,093,269. In the pyrotechnic gasgenerating agent, the highly concentrated strontium nitrate is mainlyused to keep neutral balance between oxygen and fuel; the pyrotechnicgas generating agent is mainly used in propelling agent compounds forautomobiles, gun thrusters, expansion devices, and air bags.

Existing techniques that are close to the technical scheme of thepresent invention are the techniques disclosed in patent applicationsCN1739820A, CN1150952C, and CN1222331C, wherein, CN1150952C andCN1222331C are former patent applications of the inventor. A drawback ofthe two techniques disclosed in patent applications CN1150952C andCN1222331C is: in terms of balance between fire-extinguishing efficacyand corrosion to electric apparatuses, no specific design is providedfor the requirements for insulation of different electric apparatuses.However, different types of electric apparatuses have differentwithstand capability against electrostatic accumulation or acid-alkalicorrosion at different severity levels; for example, for heavy currentelectric apparatuses such as generators, electric motors, high voltageor low-voltage apparatuses, electric networks, and cables, theinsulation resistance usually should be ≧1MΩ and <20MΩ (see thestandards of electric power industry of P. R. C., such as “Code forQuality Inspection and Assessment of Electric Apparatus InstallationEngineering (Inspection of Engineering Quality of Rotating Motors)”(DL/T5161.7-2002), etc.); for general electric apparatuses such ascommunication apparatuses, computers, onboard electric apparatuses, andelectric medical apparatuses, etc., the insulation resistance usuallyshould be ≧20MΩ and <100MΩ (see standards of electronic industry of P.R. C. and standards of communication industry of P. R. C., standards ofcomputer industry of P. R. C., such as “General Code for Semi-ConductorIntegrated Circuits” (GB6649-86), “Handbook of Surface InsulationResistance” (IPC9201), etc.); for precision electric apparatuses such asinstruments and gauges and their substrates and PCBs, the insulationresistance usually should be ≧100MΩ (see standards of electronicindustry of P. R. C., international standards of printed circuitindustry, such as “Handbook of Insulation Performance and Quality ofElectric Apparatuses for Printed Circuit Board Assembly) (IPC-CC-8308),“Requirements for Safety of Electronic Measuring Instruments” (GB4793),and “General Specification for General-Purpose Printed Circuit BoardConnectors” (GJB1717-93), etc.). Since different electric apparatuseshave different requirements for insulation resistance, it isinappropriate to use a fire-extinguishing composition with the samecomponents for different electric apparatuses in terms offire-extinguishing efficacy and cost. Therefore, the fire-extinguishingcompositions disclosed in formers patent applications of the inventorare not perfect in terms of the design of components and contents, andmust be refined for some technical features and parameters. In the priorart, no special technique on fire-extinguishing aerosol composition thatcan prevent or reduce secondary damages to electric apparatuses whilenot compromising the fire-extinguishing efficacy is found, except forthe techniques described above.

SUMMARY OF THE INVENTION

In view of the drawbacks in the prior art, the object of the presentinvention is to provide a fire-extinguishing aerosol composition, whichis more reasonable than those in the prior art, moreenvironment-friendly, suitable for general electric apparatuses, and hashigh fire-extinguishing efficacy.

The inventor's in-depth study on hot aerosol fire-extinguishingtechnique in recent years has shown: the effective fire-extinguishingconcentration depends on the quality and intrinsic physical and chemicalproperties of the fire-extinguishing agent. The combustion rate of theextinguishing agent depends on factors such as oxygen balance design andselection of oxidant and combustible, etc. To achieve the object of thepresent invention, more in-depth work must be done in several aspects:(1) design the fire-extinguishing capability with full consideration ofignition, safety, and chemical compatibility; (2) employ an oxidant thatdoesn't contain potassium salts solely, under the design principle ofnegative oxygen balance; (3) simplify the composition of compound as faras possible so as to avoid production of undesired substances.

By careful selection of oxidant and combustible, adjustment and tests ofcombustion reaction rate, tests of residue of fire-extinguishingaerosol, cooling tests, fire-extinguishing powder tests, moistureabsorption and insulation tests of solid particles, etc., the inventorfinally determine the technical scheme of aerosol fire-extinguishingcompound applicable to general electric apparatuses described in thepresent invention.

The fire-extinguishing aerosol composition provided in the present issuitable for general electric apparatuses, and comprises oxidant,combustible, adhesive, and additive; wherein, the oxidant in thefire-extinguishing composition is a mixture of potassium salt oxidantand strontium salt oxidant; the combustible is guanidine nitrate,aminoguanidine nitrate, diaminoguanidine nitrate, or a combinationthereof; the additive is aluminum powder, carbon powder, calciumcarbonate, or a combination thereof; the adhesive is epoxy resin,phenolic resin, acrylic resin, or a combination thereof; in addition,the weight percents of the components in the fire-extinguishing compoundare:

Potassium salt oxidant: ≧15% and <20%; Strontium salt oxidant: ≧48% and<52%; Combustible:    10%~25%; Additive:     2%~10%; and Adhesive:    2%~10%.

DETAILED DESCRIPTION OF THE INVENTION

The strontium salt that can be used in the fire-extinguishingcomposition is strontium nitrate, strontium peroxide, strontiumcarbonate, strontium sulphite, strontium pyrophosphate, strontiumbromide, strontium dichromate, strontium hexaboride, strontiumpermanganate, or a combination thereof; the potassium salt is potassiumnitrate, potassium chlorate, potassium perchlorate, potassium chloride,potassium nitrite, potassium carbonate, potassium citrate, or acombination thereof; alternatively the potassium salt oxidant can bepartially or completely replaced with sodium bicarbonate, sodiumnitrate, sodium perchlorate, ammonium nitrate, ammonium perchlorate,barium nitrate, cesium nitrate, or a combination thereof.

The combustible that can be used in the fire-extinguishing compositionin the present invention can be partially or completely replaced withpentaminotetrazole or salt thereof, bistetrazole or salt thereof,diazoaminotetrazole or salt thereof, diaminotetrazole dimer or saltthereof, or a combination thereof.

The additive that can be used in the fire-extinguishing composition inthe present invention can be partially or completely replaced withpyrocatechol potassium borate or salt thereof, hydroxybenzoic acid orsalt thereof, benzoic acid or salt thereof, palmitic acid or saltthereof, ammonium nitrate, potassium perchlorate, potassium chloride,copper oxide, ferric oxide, copper phthalocyanine, potassiumferricyanide, hexamethylenetetramine, or a combination thereof.

The adhesive that can be used in the fire-extinguishing composition inthe present invention can be partially or completely replaced withpolytetrafluoroethylene, ethylene polymer, nitrocellulose, trialdehydeglyceride, polyvinyl acetate, melamine resin, or a combination thereof.

The maximum mean diameter of oxidant, combustible, additive, andadhesive particles in the fire-extinguishing composition in the presentinvention is ≦50 μm.

In another preferred embodiment of the present invention, thefire-extinguishing aerosol composition comprises:

Potassium nitrate: 15%~9%; Strontium nitrate: 48%~51%; Guanidinenitrate: 10%~25%; Aluminum powder:  2%~10%; and Phenolic resin:  2%~10%.

In another preferred embodiment of the present invention, thefire-extinguishing aerosol composition comprises:

Potassium perchlorate: 15%~19%; Strontium peroxide: 48%~51%;Aminoguanidine nitrate: 10%~25%; Hydroxybenzoic acid or salt thereof: 2%~10%; and Acrylic resin:  2%~10%.

In another preferred embodiment of the present invention, thefire-extinguishing aerosol composition comprises:

Potassium nitrite: 15%~19%; Strontium permanganate: 48%~51%;Pentaminotetrazole or salt thereof: 10%~25%; Ferric oxide:  2%~10%; andEpoxy resin:  2%~10%.

In another preferred embodiment of the present invention, thefire-extinguishing aerosol composition comprises:

Potassium carbonate: 15%~19%; Strontium pyrophosphate: 48%~51%;Diazoaminotetrazole or salt thereof: 10%~25%; potassium ferricyanide: 2%~10%; and Polytetrafluoroethylene:  2%~10%.

After the fire in a space with the general electric apparatus isextinguished with the fire-extinguishing aerosol composition provided inthe present invention, the insulation resistance of the general electricapparatus is 20˜100MΩ.

The technical scheme of fire-extinguishing aerosol composition suitablefor general electric apparatuses is determined by the inventor throughcareful selection and tests on components and mixing ratios of oxidant,combustible, adhesive, and additive. The results of repeated textsdemonstrated that the insulation resistance of general electricapparatuses was greater than 20MΩ after the fire was extinguished.Compared to the prior art, the fire-extinguishing aerosol compositionprovided in the present invention attains achieves the object ofavoiding secondary damages to general electric apparatuses after thefire is extinguished, while not compromising the fire-extinguishingefficacy, and is a new generation of special and high-efficiencyfire-extinguishing aerosol composition.

DETAILED DESCRIPTION OF THE EXAMPLES

Hereunder the present invention will be described in details withreference to the examples. However, these examples shall not be deemedto constitute any limitation to the scope of the present invention.

The fire-extinguishing aerosol composition suitable for general electricapparatuses in the present invention was prepared according to theformula shown in the following table, and the insulation resistance ofprecipitant was measured as indicated in the following description.

Weight Percent of Component/% Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- Exam- Exam- Component Name ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple7 ple 8 ple 9 ple 10 Potassium perchlorate 19 15 Potassium nitrate 18 18Potassium carbonate 19 Potassium nitrite 18 Potassium chlorate Potassiumcitrate 18 Potassium bicarbonate 19 Barium nitrate 17 Sodium nitrate 16Strontium nitrate 51 50 Strontium peroxide 48 Strontium carbonate 50Strontium pyrophosphate 51 49 Strontium bromide 51 Strontiumpermanganate 51 50 51 Aminoguanidine nitrate 23 Guanidine nitrate 22 2322 20 Pentaminotetrazole 22 21 25 Diazoaminotetrazole 23 24 Aluminumpowder 5 4 Ferric oxide 4 5 Hydroxybenzoic acid 4 6 Copper oxide 5Potassium ferricyanide 2 3 Hexamethylene tetramine 5 5 Acrylic resin 6 6Polytetrafluoroethylene 5 5 6 Epoxy resin 5 5 Phenolic resin 4 6Insulation resistance 60 MΩ 67 MΩ 80 MΩ 70 MΩ 70 MΩ 66 MΩ 59 MΩ 72 MΩ 58MΩ 58 MΩ value of precipitant Note: 1. Acrylic resin: Type 104, producedby Xi'an Resin Plant; polytetrafluoroethylene: grain type, produced bySichuan Chengguang Plant; epoxy resin: type E51, produced by DalianQihua Plant; phenolic resin: type F-23, produced by Hangzhou ShunxiangPlant. 2. Measure of the insulation resistance of precipitant offire-extinguishing aerosol was carried out according to Clause 10.2 inGB499.1-2007. The testing devices included a test chamber (1 M³ (1 × 1 ×1 m)), a megohmmeter with a measuring range of 0.1MΩ-500MΩ (ZC36megohmmeter produced by Shanghai Precision Instrument Plant), culturedishes, a precision balance, and an aerosol generator. 3. The sampleplates were 100 × 100 × 1 mm white PVC plates; 100 g aerosol generationagent was pressed into a cartridge with a diameter of 40 mm and a heightof 100 mm under a pressure of 5 Mpa, and an electric starter was thenequipped into the cartridge; next, the cartridge was placed into amini-type generator; no coolant was added into the generator. 4. In thetest, a clean sample plate was placed into a culture dish with nippers.The culture dish was placed on a test stand with a height of 250 mm inthe center of a test chamber. The generator was placed at a corner inthe test chamber, with the nozzle placed against the sample plate; thepower wires were connected and the door of test chamber was closed; thedevice was powered on while counting the time with a second counter.After 20 min., the culture dish with the sample plate was taken out andthe culture dish was removed into an environmental chamber at 35° C.temperature and 90% humidity and held for 30 min.; then, the test samplewas taken out and the resistance was measured immediately.

1. A fire-extinguishing aerosol composition suitable for generalelectric apparatuses, comprising oxidant, combustible, adhesive, andadditive; wherein, the oxidant in the fire-extinguishing compound is amixture of potassium salt oxidant and strontium salt oxidant; thecombustible is selected from guanidine nitrate, aminoguanidine nitrate,diaminoguanidine nitrate, or a combination thereof; the additive isselected from aluminum powder, carbon powder, calcium carbonate, or acombination thereof; the adhesive is selected from epoxy resin, phenolicresin, acrylic resin, or a combination thereof; in addition, the weightpercents of the components in the fire-extinguishing composition are:Potassium salt oxidant: ≧15% and <20%; Strontium salt oxidant: ≧48% and<52%; Combustible:    10%~25%; Additive:     2%~10%; and Adhesive:    2%~10%.


2. The fire-extinguishing aerosol composition suitable for generalelectric apparatuses according to claim 1, wherein, the strontium saltis strontium nitrate, strontium peroxide, strontium carbonate, strontiumsulphite, strontium pyrophosphate, strontium bromide, strontiumdichromate, strontium hexaboride, strontium permanganate, or acombination thereof.
 3. The fire-extinguishing aerosol compositionsuitable for general electric apparatuses according to claim 1, wherein,the potassium salt is potassium nitrate, potassium chlorate, potassiumperchlorate, potassium chloride, potassium nitrite, potassium carbonate,potassium citrate, or a combination thereof.
 4. The fire-extinguishingaerosol composition suitable for general electric apparatuses accordingto claim 1, wherein, the potassium salt oxidant is partially orcompletely replaced with sodium bicarbonate, sodium nitrate, sodiumperchlorate, ammonium nitrate, ammonium perchlorate, barium nitrate,cesium nitrate, or a combination of them.
 5. The fire-extinguishingaerosol composition suitable for general electric apparatuses accordingto claim 1, wherein, the combustible is partially or completely replacedwith pentaminotetrazole or salt thereof, bitetrazole or salt thereof,diazoaminotetrazole or salt thereof, diaminotetrazole dimer or saltthereof, or a combination thereof.
 6. The fire-extinguishing aerosolcomposition suitable for general electric apparatuses according to claim1, wherein, the additive is partially or completely replaced withpyrocatechol potassium borate or salt thereof, hydroxybenzoic acid orsalt thereof, benzoic acid or salt thereof, palmitic acid or saltthereof, ammonium nitrate, potassium perchlorate, potassium chloride,copper oxide, ferric oxide, copper phthalocyanine, potassiumferricyanide, hexamethylenetetramine, or a combination thereof.
 7. Thefire-extinguishing aerosol composition suitable for general electricapparatuses according to claim 1, wherein, the adhesive is partially orcompletely replaced with polytetrafluoroethylene, ethylene polymer,nitrocellulose, trialdehyde glyceride, polyvinyl acetate, melamineresin, or a combination thereof.
 8. The fire-extinguishing aerosolcomposition suitable for general electric apparatuses according to claim1, wherein, the maximum mean diameter of the oxidant, combustible,adhesive, and additive particles is smaller than or equal to 50 μm. 9.The fire-extinguishing aerosol composition suitable for general electricapparatuses according to claim 1, wherein, after the fire-extinguishingaerosol composition is used to extinguish fire in a space with thegeneral electric apparatus, the insulation resistance of the generalelectric apparatus is within the range of 20-100MΩ.
 10. Thefire-extinguishing aerosol composition suitable for general electricapparatuses according to claim 1, wherein, the composition comprises:Potassium nitrate: 15%~19%; Strontium nitrate: 48%~51%; Guanidinenitrate: 10%~25%; Aluminum powder:  2%~10%; and Phenolic resin:  2%~10%.


11. The fire-extinguishing aerosol composition suitable for generalelectric apparatuses according to claim 1, wherein, the compositioncomprises: Potassium perchlorate: 15%~19%; Strontium peroxide: 48%~51%;Aminoguanidine nitrate: 10%~25%; Hydroxybenzoic acid or salt thereof: 2%~10%; and Acrylic resin:  2%~10%.


12. The fire-extinguishing aerosol composition suitable for generalelectric apparatuses according to claim 1, wherein, the compositioncomprises: Potassium nitrite: 15%~19%; Strontium permanganate: 48%~51%;Pentaminotetrazole or salt thereof: 10%~25%; Ferric oxide:  2%~10%; andEpoxy resin:  2%~10%.


13. The fire-extinguishing aerosol composition suitable for generalelectric apparatuses according to claim 1, wherein, the compoundcomprises: Potassium carbonate: 15%~19%; Strontium pyrophosphate:48%~51%; Diazoaminotetrazole or salt thereof: 10%~25%; Potassiumferricyanide:  2%~10%; and Polytetrafluoroethylene:  2%~10%.